Dropout contact by mail: a useful research tool.
D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000188:drug therapy*; D011177:Postal Service; D012959:Socioeconomic Factors; D013223:Statistics as Topic; D011795:Surveys and Questionnaires